Javaがデジタルビット数を判断する方法のまとめ

import java.util.Scanner;

public class Digits { 
  public static void main(String[] args){ 
    Scanner input=new Scanner(System.in);//        
    System.out.println("   0-999999999  ");//       
    try{ //    
    	while(true){
    int num=input.nextInt(); 
    int count = 0; 
    if (num < 0 || num > 999999999) 
    System.out.println("      "); 
    else if (num==0) 
      System.out.println("    1  "); 
    else { 
       while(num > 0){ 
      num=num / 10; 
      count++; 
       } 
       System.out.println("    "+count+"  ");
       	}
       } 
    }
    catch (Exception e){ //    
  		System.out.println("     ");
  		e.printStackTrace(); //                  
    }
  } 
}

import java.util.Scanner;

public class Digits { 
	boolean digits(int num){ //  boolean     
		 if (num < 0 || num > 999999999){
			 return true; 
		 }
		 else{
			 return false;
		 }
	}
  public static void main(String[] args){
  	Digits d=new Digits (); //    
  	Scanner input=new Scanner(System.in);//        
  	System.out.println("   0-999999999  ");//      
  	try{ //    
  		while(true){
  	int num=input.nextInt();//         
  	int count=0;
  	if(num==0){
  		System.out.println("    1  ");
  	}
  	else if(d.digits(num)){ //    digits  
  		System.out.println("      ");
  	}
  	else{
  		while(num > 0){
  			num=num / 10;
  			count++;
  			}
  		System.out.println("    "+count+"  ");
  			}
  		}
  	}
  	catch (Exception e){ //    
  		System.out.println("     ");
  		e.printStackTrace(); //                  
  	}
  } 
}